Design Follows of VCO

Figure 2.18 common design follows for RFIC. Generally we must know what kind of topology that will be used to designs VCO. Example: high output power, low phase-noise

Figure 2.18 Common VCO project design follows Consideration of VCO topology

Get design spec. and circuit goal. Use CAD software simulations (goal spec.)

Consideration of Circuits of PAD parasitic effect (circuit level)

Use Cadence Virtuoso layout and check DRC and LVS

Correct layout-rule. extract all parasitic of layout connect line and uses ADS computing that effect for circuits.(PEX)

Check Post- Simulation result data cover spec.?

Fabricate

NO

YES

(Goal spec.)

, wide turning range ...ect. Moreover circuits must be goal spec. and we design and simulate circuits uses by simulation software ADS.

This is important for RFIC. The Pad and layout lines parasitic effect often direct influence circuit performance. So about parasitic extract detail must be careful that has two methods to equivalent pad parasitical quantities: 1.uses equivalent circuit illustration Figure 2.19:

Fig 2.19 pad & bonding wire equivalent circuit

The values are appraised. Pad C≅ 60fF, R ≅ 250Ohm, L ≅ 2nH and parasitical-resistor about 10Ohm. 2: uses EM software (ADS Momentum, HFSS and IE3D) to extract pad layout 2-port S-parameter substitute circuit illustration Fig 2.20:

Bond wire

Pad

(a) (b)

Figure 2.20 (a) S-parameter of substitute circuit (b) extrication of pad layout

We substitute the circuits by employ EM software extract data s-parameter file SXP(X=1,23…) and run simulation again that has almost get real characteristic before fabrication.(because maybe have some manufacturing process inaccuracy),we say parasitical-

quantity maybe make circuit fail , so we usually incessant check S-parameters of layout lines whether it influence the origin (goal) circuit characteristic or not and do some fixes on circuits to keep circuit characteristic.

Chapter 3

Design of Low-Power Current-Reused CMOS VCO

In this chapter, we will introduce to design of low power VCO. Low phase-noise is very important for any wireless communication systems that want to get low phase-noise and low power. We need some circuits techniques reach it. In below section, we will introduce low power structure circuit and explain it what different to convention.

3.1 Induction of Low-Power Current-Reused VCO Structure

In mobile and portable communication equipment the supply voltage should be as low as possible. To increase equipment operating time, this shows how importance of low-power circuits. A voltage controlled oscillator (VCO) is an important block and among the blocks of any transceiver that applied in mobile and portable equipments.

Show Figure3.1,It is low-power VCO structure[6] that uses one current path improve on conventional VCO circuits and the two currents path by this way in generally can reduce half current costs in the circuits.

Figure 3.1 Schematic of the basic topology of current-reused Differential LC-VCO [6]

The VCO be used P-MOS and N-MOS transistors in the cross-connected pair. The P&N-MOS can be reduced by half supply current and the degeneration source resistors can reduce body effect and improve magnitude symmetry of output signals. Also it is only one current the core power-consumed will be controlled.

Figure 3.2 Shows N-PMOS cross pair large-signal equivalent circuits, left circuit is no resistance original circuit that will discuss this form here, middle circuit is first-half period equivalent circuit (when the voltage at node X is high and low) and two parasitic capacitances Cx=C/2+Cpx and Cy=C/2+Cpy respectively from P-NMOS. The first-half period

During the first half-period as shown in the Figure 3.2, the M1 and M2 are ON and the current flows from VDD through the turning inductor L to ground. During the second half-period, the M1 and M2 are off and the current flows in the opposite direction through the capacitors Cx and Cy. (Note that in the conventional differential VCO, the cross-connected transistors switch alternately, the P-N MOSFETs switch at the same time. During the first half-period of oscillation, the P-N MOSFETs operate in triode mode near the peak of the voltage swing.

.

Figure 3.2 N-PMOS cross pair large-signal equivalent circuit [6]

n

gmp gmn

G gmp gmn Rs gmp gmn

= − ⋅

+ + ⋅ ⋅ (3.1)

From Equation (3.1), Gn (negative conductance) of Figure 3.1 gmp(transconductance of PMOS) , gmn (transconductance of NMOS) and source resistor Rs.

3.2 Design of Low-Power Current-Reused VCO for L-Band System

The L-band application uses frequencies from 1GHz to 2GHz that covered some mobile broadcast band like T-DMB, DVB-H, GPS, Galileo and some cell-phone band likes WCDMA, so lower power-consumed device development is requested. In next section, we will show my circuits that not only use in L-band and the other circuit uses on new wireless application WiMAX.

3.3 VCO Simulation and Measurements for L-Band System

3.3.1 Design of Structure

In this chapter, all circuit uses current-reused topology that has low-current and saves Power, because the N-P MOS pair operates in triode region near the peak of the voltage swing, the voltage swing is only limited by the power supply and can use source Rs to control the DC as current well as the peak dynamic current.

Show in Figure 3.2, this circuit used in L-Band application and the fabricated by TSMC 0.18μm mixed signal/RF CMOS 1P6M process technology. It is a 1.8V and current 1mA

low-power CMOS voltage-controlled oscillator with the output buffer is matched to 50 ohm for standard. The output buffer used 1V voltage supplyand current 3.77mA (Left) and 3.74mA (Right) two sides respectively.

Figure 3.3 Schematic of the basic topology of current-reused VCO with output-buffers

3.3.2 L-Band VCO Simulation Characteristics

The study of circuit simulated, analyzed and extracted layout parasitic by Agilent-ADS software. The VCO core operates voltage, current, power-consumed, 1.8V and 1mA, 1.854mW respectively and output power is -4.375dBm.

Shown in Figure 3.4 oscillation frequency at 1.61 Ghz and has -15dbm 2^nd harmonic error value. Figure 3.5 turning range is from 1.367 GHz to 1.639 Ghz. The phase noise 100 KHz and 1MHz offset are -107 dBc/hz and -128.388 dBc/hz respectively. The total specifications are shown in Table 3.1.

In Table 3.2 and 3.3 are manufacture process and temperature variation respectively.

The simulation are little variation results that can be accepted.

( No manufacture processing variation and interconnect effect ) Transient Characteristics

Figure 3.4 Transient simulation of L-band current-reused VCO

Harmonic Characteristics

Turning Range

Figure 3.5 Turning range simulation of L-band current-reused VCO

Phase-noise ：

Figure 3.6 Phase-noise simulation of L-band current-reused VCO

Table 3.1 Simulation specifications of L-band current-reused VCO

Operation Voltage 1.8 V

Operating Frequency 1.367GHz ~1.639GHz

Turning Range 19.21%

Power consumption

(core) 1.854mW

#

Power consumption

(Buffer) 7.51mW

Pout.(dBm) -4.375

Phase-Noise@100KHz (dBc/Hz) -107

Phase-Noise@1MHz(dBc/Hz) -128

(#) Power consumption(Buffer) Total of two side buffer power-consumed

(Manufacture processing variation)

Table 3.2 Manufacture processing variation of L-band current-reused VCO Manufacture processing variation results

(#) Power consumption(Buffer) Total of two side buffer power-consumed

(Temperature variation)

Table 3.3 Temperature variation of L-band current-reused VCO

Temperature variation results

(#) Power consumption(Buffer) Total of two side buffer power-consumed

(With interconnect line effect - Post Simulation)

The interconnect lines impact circuits characteristics that maybe make circuit function fail without extracting interconnect line. Illustration Figure 3.7 slant lines was extracted interconnect lines and uses less and short interconnect lines in layout design that makes sure the circuit stable and decrease some don’t need parasitism. We used Agilent ADS Momentum to simulation this experiment.

Figure 3.7 Interconnect lines extraction of L-band current-reused VCO

characteristic.

Shown in Figure 3.8 oscillation frequency at 1.6 Ghz and has -17.56 dBm 2^nd harmonic error value. Figure 3.9 turning range is from 1.357 GHz to 1.626 Ghz. The phase noise 100 KHz and 1MHz offset are -107.67 dBc/hz and -128.332 dBc/hz respectively. The post/pre simulation specifications are shown in Table 3.4 and Table 3.5 reference of VCO comparability.

Shown In Figure 3.11 and 3.12 are layout and microphotograph of VCO respectively.

Post-simulation results

Transient Characteristics

Figure 3.8 Transient post-simulation of L-band current-reused VCO

Harmonic Characteristics Turning Range

Figure 3.9 Turning range post-simulation of L-band current-reused VCO

Phase-Noise：

Figure 3.10 Phase-noise post-simulation of L-band current-reused VCO

Table 3.4 L-band current-reused VCO Results of Post-simulation and pre-simulation Post- simulation Per- simulation

Operation Voltage 1.8 V 1.8 V

Operating Frequency 1.357GHz

~1.626GHz

1.367GHz

~1.639GHz

Turning Range 18.036% 19.21%

Power consumption

(core) 1.85mW 1.854mW

#

Power consumption

(Buffer) 7.51mW 7.51mW

Pout.(dBm) -4.2 -4.375

Phase-Noise@100KHz (dBc/Hz) -107 -107

Phase-Noise@1MHz(dBc/Hz) -128 -128

(#) Power consumption(Buffer) Total of two side buffer power-consumed

Table 3.5 Reference of L-band current-reused VCO Results compare

Measurement 1.25V CMOS

0.18um 2G N/A 1mW -7.4 -103 ~-121

N/A 3.4mW N/A N/A

-122.42@2.4G

-123.43@4.7G

Figure 3.11 Layout of L-band current-reused VCO

Figure 3.12 Microphotograph of L-band current-reused VCO

3.3.3 L-Band VCO Measurement Characteristic

In this section, we will discuss Measurement results. The Measurement results demonstrate the central oscillation signal of 1.49 GHz to be associated with the 269 MHz turning range and -125 dBc/Hz phase noise at 1 MHz offset. The power consumption of the VCO core is only 1.8 mW. The Measurement result evaluated by means of a figure of merit is about 186.11 dBc/Hz by equation (3.2).

{ }

^10log

^fm

^{2 DC}

FOM L fm P

fo

⎡⎛ ⎞ ⎤

⎢ ⎥

= + ⎢⎣⎜⎝ ⎟⎠ ⎥⎦

(3.2)

Figure 3.13 Measurement Phase Noise result of L-band current-reused VCO

Figure 3.14 Measurement current result of L-band current-reused VCO

Figure 3.15 Measurement turning range result of L-band current-reused VCO

Figure 3.16 Measurement output power result of L-band current-reused VCO

Table 3.6 Results of simulation and Measurement

Spec. Simulation Measurement

Result

Voltage

1.8 V 1.8V

Current(core)

1.02mA 1mA

Frequency

1.357GHz ~1.626GHz 1.24G~1.46G

Output-power Pout.(dBm)

-4.2dBm -3.37dBm

Power consumption (total)

1.85mW 1.8mW

Turning Range

18.04% 16.30%

Phase-Noise@100KHz

-107.6 ~ -100

Phase-Noise@1MHz

-128.33 -123~-125.35

FOM

-189.91(1.836mW)@1M -186.11(1.8mW) @1M

Die Size

1.36 X 1.29 mm

3.4 Design of Low-Power Current-Reused VCO for WiMAX FWA System

The WiMAX FWA (Fixed Wireless Access) is fixed technology that didn’t like mobile application can use in pocket devices. But he has some advantage just like high transmission speed and high distance range. In this section, the VCO is application in IEEE 802.16e WMAX Fixed Wireless Access (FWA) under 2.50 ~ 2.69GHz.

3.5 VCO Simulation and Measurements for WiMAX FWA 3.5.1 Design of Structure

The main structure is the same for above L-band VCO. But we use source follower Buffer for some reason. Using source follower structure can get wide-band matching that can prevent manufacture processing variation and also influence buffer matching band variation than common source structure.

Figure 3.17 Schematic of the WiMAX FWA current-reused VCO with source follower output-buffers

3.5.2 WiMAX FWA VCO Simulation Characteristics

The study of circuit simulated, analyzed and extracted interconnect lines parasitic by Agilent-ADS software. The VCO core operates voltage, current, power-consumed, 1.5V and 4.1mA, 1.669mW respectively and output power is -5.9dBm and operation frequency 3.142GHz~3.839GHz turning range 19.954% phase-noise -126.3dBc/Hz at 1MHz offset frequency in pre-simulation.

Shown in Figure 3.18 oscillation frequency at 3.1 Ghz and has -24.68 dBm 2^nd harmonic error value. Figure 3.19 turning range is from 3.14 GHz to 3.83 Ghz. The phase noise 100 KHz and 1MHz offset are -104.65 dBc/hz and -126.309 dBc/hz respectively. The total specifications are shown in Table 3.7.

In Table 3.8 and 3.9 are manufacture processing and temperature variation respectively.

The simulation are little variation results that can be accepted.

Shown in Figure 3.23 oscillation frequency at 3.36 Ghz and has -25.08 dBm 2^nd harmonic error value. Figure 3.24 turning range is from 3.34 GHz to 3.91 Ghz. The phase noise 100 KHz and 1MHz offset are -101.17 dBc/hz and -123.46 dBc/hz respectively. In Table 3.11 and 3.12 are manufacture processing and temperature variation respectively.The post/pre simulation specifications are shown in Table 3.13 and Table 3.14 reference of VCO compare. Shown In Figure 3.26 and 3.27 are layout and microphotograph of VCO respectively.

( No manufacture processing variation and interconnect effect ) Transient Characteristics

Figure 3.18 Transient post-simulation of WiMAX FWA current-reused VCO

Harmonic Characteristics

Turning Range

Figure 3.19 Turning range post-simulation of WiMAX FWA current-reused VCO

Phase-Noise：

Figure 3.20 Phase-noise post-simulation of WiMAX current-reused VCO

Table 3.7 WiMAX FWA current-reused VCO of simulation specifications

Operation Voltage 1.5 V

Operating Frequency 3.142GHz ~3.839GHz

Turning Range 19.954%

Power consumption

(core) 6.15mW

#

Power consumption

(Buffer) 1.669mW

Pout.(dBm) -5.9

Phase-Noise@100KHz (dBc/Hz) -104.6

Phase-Noise@1MHz(dBc/Hz) -126.3

(#)

Power consumption(Buffer) Total of two side buffer power-consumed

( No manufacture processing variation and interconnect effect )

Table 3.8 Manufacture processing variation of WiMAX FWA current-reused VCO Manufacture processing variation results TT FF SS SF FS Turning Range(%) 19.9 19.5 20.3 20.3 19.8 Pout (dBm) -5.9 -12 -11 -9 -14 Phase-Noise@100KHz (dBc/Hz) -104.5 -104.6 -102.2 -104.8 -103.9 Phase-Noise@1MHz (dBc/Hz) -126.2 -126.4 -125.2 -126 -126.2

Table 3.9 Temperature variation of WiMAX FWA current-reused VCO

Temperature variation results

-25 25 85

Turning Range

20.6% 19.9% 19.3%

P^out

(dBm) -5.5 -5.9 -11

Phase-Noise@100KHz (dBc/Hz)

-106 -104.6 -102.7

Phase-Noise@1MHz (dBc/Hz)

-127.7 -126 -124.5

(With interconnect line effect - Post Simulation)

Figure 3.21 Interconnect lines extraction of WiMAX FWA current-reused VCO

Figure 3.22 Interconnect lines extraction of WiMAX FWA current-reused VCO for layout

Post-simulation results Transient Characteristics

Figure 3.23 Transient post-simulation of WiMAX FWA current-reused VCO

Harmonic Characteristics

Turning Range

Figure 3.24 Turning range post-simulation of WiMAX FWA current-reused VCO

Phase-Noise：

Figure 3.25 Phase-noise post-simulation of WiMAX FWA current-reused VCO

Table 3.10 Results of Post-simulation of WiMAX FWA

Operation Voltage 1.5 V

Operating Frequency 3.341GHz ~3.912GHz

Turning Range 15.743%

Power consumption

(core) 5.95mW

#

Power consumption

(Buffer) 1.737mW

Pout.(dBm) -8.37

Phase-Noise@100KHz (dBc/Hz) -101.17

Phase-Noise@1MHz(dBc/Hz) -123.46

(#) Power consumption(Buffer) Total of two side buffer power-consumed

Table 3.11 Manufacture processing variation with interconnect effect of WiMAX FWA current-reused VCO

Table 3.12 Temperature variation with interconnect effect of L-band current-reused VCO Temperature variation results

Table 3.13 Results of Post-simulation and pre-simulation

Post-Simulation Pre- Simulation

Operation Voltage 1.5 V 1.5 V

Operating Frequency 3.341GHz ~3.912GHz 3.142GHz ~3.839GHz

Turning Range 15.743% 19.954%

Power consumption

(core) 5.95mW 6.15mW

#

Power consumption

(Buffer) 1.737mW 1.669mW

Pout.(dBm) -8.37 -5.9

Phase-Noise@100KHz

(dBc/Hz) -101.17 -104.6

Phase-Noise@1MHz(dBc/Hz) -123.46 -126.3

(#) Power consumption(Buffer) Total of two side buffer power-consumed

Manufacture processing variation results

Table 3.14 reference of WiMAX FWA current-reused VCO Results compare

PDC

(mW) Pout.

Ref. ^supply

voltage Technol. Freq. Turning Range

Measurement 1.2V CMOS

90-nm 5.6Ghz 9.50% 0.52 -3 N/A -112

Figure 3.26 Layout of WiMAX FWA current-reused VCO

Figure 3.27 Microphotograph of WiMAX FWA current-reused VCO

3.5.3 WiMAX FWA VCO Measurement Characteristics

In this section, The Measurement results demonstrate that central oscillation signal of 3.2 GHz with the 500 MHz turning range, 2.82 to 3.35 GHz but in this case. We got some VCO steady problem in phase-noise. we will discuss late, About power-consumption which we trade-off between power-consumption and phase-noise. Usually we hope to get as low phase-noise as possible. So we expense some power-consumption to get lower phase-noise and the VCO core is about 6.15 mW.

(a)

(b)

Figure 3.28 Measurement result of WiMAX FWA current-reused VCO spectrum (a) Normal state (b) frequency per 2 by divider

Show illustration 3.28 (a) (b) and 3.29, we can see very dirty spectrum in Figure 3.28(a) (b) that occurred acute of signal frequency and the target frequency variation form

0.5M~1MHz. So we can’t get stable frequency to Measurement phase-noise during our Measurement. By above reason, we conjecture that due to we used too long-length

interconnect to connect body to Vbody PAD(ref. figure 3.26) which pass through and too close inductance , signal output line and inductance Guard.-Ring that made much noise-signal coupling to capacitor to MOS’s body and direct influence circuits. Show Figure.3.29 that result to show no frequency locked and instrument can’t find real center carrier frequency to plot normal tendency of phase-noise.

Figure 3.29 Measurement phase-noise-instable result of WiMAX FWA current-reused VCO

Figure 3.30 Measurement turning range result of WiMAX FWA current-reused VCO

Figure 3.31 Measurement Vtune V.S. current result of WiMAX FWA current-reused VCO

Figure 3.32 Measurement output power result of WiMAX FWA current-reused VCO

Show Figure 3.31 and 3.32 VCO Vtune V.S. current /output power (dBm) respectively that had very close result with simulation.

Table 3.15 Simulation and Measurement results of WiMAX FWA VCO

Simulation Measurement

Spec. Result

Voltage

1.5 V 1.5V

Current(core)

3.96mA 4.1mA

Frequency

3.341~3.912GHz 2.82G-3.35G

Output

power_Pout.(dBm)

-8.37dBm -8 ~ -10dBm

Power consumption

(total)

5.53mW 6.15mW

Turning Range

15.74% 16.73%

Phase-Noise@100KHz

-101.17 - X (instable)

Phase-Noise@1MHz

-123.46 - X(instable)

FOM

-187.56_1M_3.91G

-186.19_1M_3.34G - X(instable)

Die Size 1.13 X 1.05 mm

3.6 Discussion and Summary

Two different bands Current-Reused Configuration of VCO are introduced in this chapter. In above sections, the Current-Reused Configuration can use one path current to get half power-consumed that difference than convention VCO [6] two path currents. In the phase-noise characteristic, we optimize inductance Q factor and find the maximum value that

not only can got most sharp spectrum but also got good phase-noise. The Low-Power CMOS Voltage-controlled oscillator (VCO) had built by current-reused configuration with Output-Buffer fabricate by TSMC 0.18μm mixed signal/RF 1P6M process. A Good performance was Measurement with this design. The VCO circuit resonator was application on 1.24G~1.46G and 2.82G-3.35G 2.21~2.39 GHz respectively, the turning voltage two VCO both bias voltage between 0 to 1.8 V, Output power -3.37dBm and -8dBm and phase-noise -125.35 dBc/Hz at 1-MHz offset frequency(L-band). The power consumption of the VCO (core) only 1.8mW at 1.2V and 6.15mW at 1.5V voltage supply.

Figure 3.33 Discusser layout of WiMAX FWA current-reused VCO MOS body

Interconnect line of Vbody

1

2

3

Three fail reasons are shown in Figure 3.33. The fail resins we conclude are unsuitable position of interconnection line. In our comment, that reason 1(square_no.1): VCO output signal coupling to Vbody interconnect line and noise pass through into P-MOS capacitor.

Reason 2(square_no.2): The inductance Guard-Ring connects to ground not average in this case and Guard-Ring is use M1 connect to ground, our body interconnect line also the same that. So noise very easy coupling to there. Reason 3(square_no.3): This is M1 to M6 coupling capacitance. In this case, we neglect that effect in parasite extraction at EM-simulation and that by reason 1 and 2 maybe output signal and guard-ring noise also coupling to LC resonator. Form above reasons, instable and shift frequency maybe by that.

Therefore, above Noise Current experiment prove our problem point at this issue.It is shown in Figure 3.34. It is injected 50

μ

A current noise into body pad.

Figure 3.34 Noise Current experiment for proving instable oscillation

The simulation results can refer to Figure 3.36 and normal state shown in Figure 3.35.

Normal State

Figure 3.35 Noise Current experiment for proving instable oscillation-normal state Noise Injected (Noise_50

μ A)

Figure 3.36 Noise Current experiment for proving instable oscillation-noise injected Shown in Figure 3.35 .The turning range is from 3.85GHz to 3.25GHz and has regular output spectrum at no-noise injected state. We can refer to Figure 3.36 when has been

3.61G

3.85G

injected 50

μ

A noise current which influence circuit regular oscillation, turning range became form 3.61GHz to 3.24GHz and has deformed spectrum maybe is reason of instable which the difference in frequency between the normal and the noise injected there is 240MHz and has 150MHz frequency inaccuracy in our substrate. In above proved to result between simulation and Measurement.

Chapter 4

Design of Low-Power Current-Reused with Balance Resistors CMOS VCO

4.1 Induction of Current-Reused VCO with Balance Resistors Structure

Figure. 4.1 shown the architecture of Current-Reused Configuration with balance resistors Included Output-Buffer VCO.

Figure.4.1 The Current-Reused Configuration with balance resistors topology. Rbr

(balance resistors topology negative impedance) could be derived as equation (4.1) [7] and assume gmp equal gmn could be derived as equation (4.2).

Figure.4.1 Schematic of the Current-Reused Configuration with balance resistors Include Output-Buffer VCO

( 1/ ) ( 1/ )

This replace resistor makes NMOS direct-connect to ground which is not only remove the body effect but also enhance negative feed-back. In other way, the balance resistors can balance MOS on/off-time status. The buffer use common-Source stage to make sure output is 50-Ohm match and quarantines DC current leak out.

4.2 Design of Current-Reused VCO with Balance Resistors for WiMAX WSC System

The WiMAX (Mobile worldwide interoperability for microwave access) is a wireless standard that introduces orthogonal frequency division multiple access (OFDMA) and other key features to enable mobile broadband services at a vehicular speed of up to 120 km/h.

WiMAX complements the and competes with wireless local area networks (WLANs) and the third generation (3G) wireless standards on coverage and data rate. The WiMAX standard supports both fixed and mobile broadband data services[18]. That means have a much larger market in this field.

4.3 Current-Reused VCO with Balance Resistors VCO Simulation and Measurement

In this section, a 1.2V Low-Power CMOS Voltage-controlled oscillator (VCO) build by current-reused configuration with Output-Buffer and two drain resistors used in order to improve magnitude symmetry of output signals for IEEE 802.16e, by TSMC 0.18μm mixed signal/RF process. A Good performance was measured with this design. The VCO circuit resonator was applied between 2.21~2.39 GHz under the turning voltage between 0 to 1.2 V 、 Output power -4.2dBm and phase-noise -121dBc/Hz at 1-MHz offset frequency. The power consumption of the VCO only 3.96mW at 1.2V voltage supply with buffer included.

4.3.1 Design of Structure

The relate of product will present the Mobile WiMAX standard. In this Paper The VCO application in IEEE 802.16e WMAX Wireless Communication Services (WCS) under 2.21~2.39 GHz coverage 2.305-2.320GHz, 2.345-2.360GHz of WCS.

In mobile and portable communication equipment the supply voltage should be as low as possible. To increase equipment operating time, this shows how importance of low-power circuits. A voltage controlled oscillator (VCO) is an important block among the blocks of any transceiver that applied in mobile and portable equipments.

In wireless transceivers, VCO the power mostly consume the power mostly. VCOs implemented in silicon-based technologies are mainly realized as differential cross-coupled topologies due to the poor substrate isolation properties of silicon based technologies. In this paper, the proposed VCO uses P-MOS and N-MOS transistors in the cross-connected pair.

The P and N-MOS can be reduced by half supply current and two drain resistors not only improve magnitude symmetry of output signals but also improving negative conductance. It

The P and N-MOS can be reduced by half supply current and two drain resistors not only improve magnitude symmetry of output signals but also improving negative conductance. It

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