Chang-Woo Kim

A 2.7-V SiGe HBT variable gain amplifier for CDMA applications

A monolithic SiGe HBT variable gain amplifier with high dB-linear gain control and high linearity has been developed for CDMA applications. The VGA achieves a 30-dB dynamic gain control with a control range of 0-2.7 Vdc in 824-849 MHz band. The maximum gain and attenuation are 23 dB and 7 dB, respectively. Input/output VSWRs keep low and constant despite change in the gain-control voltage. At a low operation voltage of 2.7 V, the VGA produces a 1-dB compression output power of 13 dBm and /spl plusmn/885-kHz ACPR of -57 dBc at a 5-dBm output power.

A 34% tuning range CMOS VCO with linear frequency tuning

A CMOS voltage controlled oscillator(VCO) with additional parallel resistors in its LC resonator has been proposed to improve the tuning (frequency-to-voltage) linearity and reduce the tuning sensitivity KVCO. The VCO is linearly tunable from 806 to 1,113 MHz with a 34% tuning range controlled linearly by the tuning voltage. The phase noise of the VCO is −100.4 dBc/Hz at 100-kHz offset frequency from 903MHz carrier. The supply voltage was 1.8V with the current of 2.5 mA flowing through the differential core. The chip size is 0.815 × 0.680 mm2, which has been fabricated in a standard 180-nm CMOS technology.

A 8-GHz SiGe HBT VCO Design on a Low Resistive Silicon Substrate Using GSML

A practical layout method called ground shield microstrip lines (GSML) is investigated for the reliable design of high frequency interconnection lines on a low resistive silicon substrate. GSML facilitates the prediction of parasitic networks at the expense of introducing negligible loss. The microwave performance of a GSML line structure is compared to that of a conventional metal line on the same standard silicon substrate (20 Omegamiddotcm). Then, the GSML structure is applied to an 8-GHz SiGe heterojunction bipolar transistor (HBT) voltage-controlled oscillator (VCO) circuit. The GSML method replaces the post layout simulation and reduces iteration time, increasing design efficiency. A fully integrated differential tuning SiGe HBT 8-GHz VCO is designed and tested. The measured phase noise for the VCO is dBc/Hz at 1-MHz offset with an output power of dBm.

A dual band SiGe MMIC LNA and mixer with ground shield for WCDMA and CDMA applications

A single chip 2.7 V dual band SiGe RF front end for 2140 MHz WCDMA and 882 MHz CDMA operation has been implemented by a standard SiGe bipolar process with an f/sub max/ of 50 GHz utilizing a ground shield layer structure upon low resistive silicon substrate. The LNAs are gain controllable single stage amplifiers with high linear characteristics. The mixer circuits are double balanced Gilbert (1997) type micro-mixers with differential IF buffer amplifiers.

4-8 GHz band SiGe HBT variable gain amplifiers with a feedforward configuration

Broadband monolithic SiGe HBT variable gain amplifiers with a feedforward configuration have been newly developed to improve bandwidth and dB-linearly controlled gain characteristics. For bias-current control, two types of the VGA have been made: one using a coupled-emitter resistor and the other using a HBT-based current source. Both of the VGAs achieve a dynamic gain-control range of 20 dB and a 3-dB bandwidth of 4 GHz (4-8 GHz) with the control-voltage range from 0.4 to 2.6 V. At 6 GHz, the VGAs with an emitter resistor and a current source produce a maximum gain of 9.3 dB and 8.8 dB, respectively. The total bias currents are 59 mA in the VGA with an emitter resistor and 71 mA in that with a constant current source at V/sub CTRL/ = 2.4 V.

An Wideband GaN Low Noise Amplifier in a 3×3 mm2Quad Flat Non-leaded Package

An ultra-compact and wideband low noise amplifier (LNA) in a quad flat non-leaded (QFN) package is presented. The LNA monolithic microwave integrated circuit (MMIC) is implemented in a 0.25 μm GaN IC technology on a Silicon Carbide (SiC) substrate provided by Triquint. A source degeneration inductor and a gate inductor are used to obtain the noise and input matching simultaneously. The resistive feedback and inductor peaking techniques are employed to achieve a wideband characteristic. The LNA chip is mounted in the 3×3-mm 2 QFN package and measured. The supply voltages for the first and second stages are 14 V and 7 V, respectively, and the total current is 70 mA. The highest gain is 13.5 dB around the mid-band, and -3 dB frequencies are observed at 0.7 and 12 GHz. Input and output return losses (S11 and S22) of less than -10 dB measure from 1 to 12 GHz; there is an absolute bandwidth of 11 GHz and a fractional bandwidth of 169%. Across the bandwidth, the noise figures (NFs) are between 3 and 5 dB, while the output-referred third-order intercept points (OIP3s) are between 26 and 28 dBm. The overall chip size with all bonding pads is 1.1×0.9 mm 2 . To the best of our knowledge, this LNA shows the best figure-of-merit (FoM) compared with other published GaN LNAs with the same gate length.

A Cancellation Technique of TX Leakage Signal for Emhanced Readability in UHF-band RFID Readers

In order to improve readability, a leakage-signal canceller has been proposed in UHF-band RFID readers. The proposed canceller is composed of two blocks: an environment monitoring block for detection of Tx and RX power levels and a leakage cancellation block. The leakage canceller consists of directional-couplers, digital attenuators and phase shifters based on the feed-forward scheme. The leakage canceller is located between antenna and reader. An improved experimental characterization of the scheme is presented with results from the reader operating in the Korean RFID frequency band, conforming the validity of the approach with more than 29 dB of leakage cancellation.

8 GHz high conversion gain Darlington mixer

This paper describes a new Darlington AC-coupled mixer operating at 8 GHz with improved figure-of-merits. This Darlington AC-coupled mixer along with a simple AC- coupling mixer used for reference are implemented in a 0.35 mum SiGe bipolar process. The supply voltage and current consumption are 3.2 V and 28 mA. In the Darlington AC-coupling mixer, the conversion gain, the operating bandwidth, and the NF are found to be improved by 13 dB, 180 MHz, and 10 dB, respectively. These improved figure-of-merit results from the use of the Darlington cell in the transconductance stage of the AC-coupling mixer.

A 2.7-V monolithic SiGe HBT variable gain amplifier for CDMA applications

A monolithic SiGe HBT variable gain amplifier with high dB-linear gain control and high linearity has been developed for CDMA applications. The VGA achieves a dynamic gain control range of 30 dB with 2.7-Vdc control-voltage range in 824-849 MHz. The maximum gain and attenuation at a center frequency of 835 MHz are 23 dB and 7 dB, respectively. Input/output VSWR keep low and constant despite change in the gain-control voltage. At a low operation voltage of 2.7 V the VGA produces a output power of 5 dBm with 20 dB power gain and -57 dBc ACPR at /spl plusmn/885 KHz offset bands.