This paper presents a differential low power low noise amplifier designed for the wireless sensor network （WSN） in a TSMC 0.18μm RF CMOS process.A two-stage cross-coupling cascaded common-gate（CG） topology has been designed as the amplifier.The first stage is a capacitive cross-coupling topology.It can reduce the power and noise simultaneously.The second stage is a positive feedback cross-coupling topology,used to set up a negative resistance to enhance the equivalent Q factor of the inductor at the load to improve the gain of the LNA.A differential inductor has been designed as the load to achieve reasonable gain.This inductor has been simulated by the means of momentum electromagnetic simulation in ADS.A ＂double-π＂ circuit model has been built as the inductor model by iteration in ADS.The inductor has been fabricated separately to verify the model. The LNA has been fabricated and measured.The LNA works well centered at 2.44 GHz.The measured gain S_（21） is variable with high gain at 16.8 dB and low gain at 1 dB.The NF（noise figure） at high gain mode is 3.6 dB,the input referenced 1 dB compression point（IP1dB） is about -8 dBm and the IIP3 is 2 dBm at low gain mode.The LNA consumes about 1.2 mA current from 1.8 V power supply.
This paper presents a low noise amplifier（LNA）,which could work at an ultra-low voltage of 0.5 V and was optimized for WSN application using 0.13μm RF-CMOS technology.The circuit was analyzed and a new optimization method for a folded cascode LNA was introduced.Measured results of the proposed circuit demonstrated a power gain of 14.13 dB,consuming 3 mW DC power,showing 1.96 dB NF and an input 1-dB compression point of -19.9 dBm.Both input power matching（S_（11）） and output power matching（S_（22）） were below -10 dB.The results indicate that this LNA is fully applicable to low voltage and low power applications.
A 5-GHz CMOS programmable frequency divider whose modulus can be varied from 2403 to 2480 for 2.4-GHz ZigBee applications is presented.The divider based on a dual-modulus prescaler（DMP） and pulse-swallow counter is designed to reduce power consumption and chip area.Implemented in the 0.18-μm mixed-signal CMOS process,the divider operates over a wide range of 1-7.4 GHz with an input signal of 7.5 dBm;the programmable divider output phase noise is -125.3 dBc/Hz at an offset of 100 kHz.The core circuit without test buffer consumes 4.3 mA current from a 1.8 V power supply and occupies a chip area of approximately 0.015 mm^2.The experimental results indicate that the programmable divider works well for its application in frequency synthesizers.
This paper presents a variable gain low-noise amplifier（VG-LNA） for 5 GHz applications.The effect of the input parasitic capacitance on the inductively degenerated common source LNA＇s input impedance is analyzed in detail.A new ESD and LNA co-design method was proposed to achieve good performance.In addition,by using a simple feedback loop at the second stage of the LNA,continuous gain control is realized.The measurement results of the proposed VG-LNA exhibit 25 dB（-3.3 dB to 21.7 dB） variable gain range,2.8 dB noise figure at the maximum gain and 1 dBm IIP3 at the minimum gain,while the DC power consumption is 9.9 mW under a 1.8 V supply voltage.
A new high performance charge pump circuit is designed and realized in 0.18μm CMOS process. A wide input ranged rail-to-rail operational amplifier and self-biasing cascode current mirror are used to enable the charge pump current to be well matched in a wide output voltage range.Furthermore,a method of adding a precharging current source is proposed to increase the initial charge current,which will speed up the settling time of CPPLLs.Test results show that the current mismatching can be less than 0.4%in the output voltage range of 0.4 to 1.7 V,with a charge pump current of 100μA and a precharging current of 70μA.The average power consumption of the charge pump in the locked condition is around 0.9 mW under a 1.8 V supply voltage.
A new broadband low-noise amplifier （LNA） is proposed. The conventional common gate （CG） LNA exhibits a relatively high noise figure, so active gin-boosting technology is utilized to restrain the noise generated by the input transistors and reduce the noise figure. Theory, simulation and measurement are shown. An implemented prototype using 0.13 μm CMOS technology is evaluated using on-wafer probing. S11 and S22 are below -10 dB across 0.1-5 GHz. Measurements also show a gain of 18.3 dB with a 3 dB bandwidth from 100 MHz to 2.1 GHz and an ⅡP3 of-7 dBm at 2 GHz. The measured noise figure is better than 2.5 dB below 2.1 GHz, is better than 4.5 dB below 5 GHz, and at 500 MHz, it gets its minimum value 1.8 dB. The LNA consumes 9 mA from 1.5 V supply and occupies an area of 0.04 mm^2.
