R. Esfandiari

A novel HBT distributed amplifier design topology based on attenuation compensation techniques

We report on a novel HBT distributed amplifier design which achieves the highest gain-bandwidth product (GBP) per device f/sub T/ so far reported for HBT distributed amplifiers. This paper introduces a new design topology for HBT DAs which incorporates attenuation compensation on both the input and output transmission lines. A four-section HBT DA using this novel topology achieves a gain of 15 dB and a 3-dB bandwidth of >15 GHz. The resulting gain-bandwidth product is 84 GHz. When normalized to the device f/sub T/, this DA achieves the highest normalized gain-bandwidth-product figure of merit for HBT DAs, /spl ap/3.67, which is a 55% improvement over existing state-of-the-art performance. Attenuation compensation of the input transmission line is realized using HBT active impedance transformations. The resulting transistor configuration consists of a common-collector driving a common-emitter-cascode transistor pair. This configuration offers 15-20 dB more available gain for the device unit cell, and results in gain-bandwidth product improvements of 200% over a conventional common-emitter DA configuration. This paper discusses the design theory, techniques, and measurements of this newly developed HBT distributed amplifier topology. >

GaAs HBT wideband matrix distributed and Darlington feedback amplifiers to 24 GHz

The designs and performances of a 2-24 GHz distributed matrix amplifier and 1-20 GHz 2-stage Darlington coupled amplifier based on an advanced HBT MBE profile that increases the bandwidth response of the distributed and Darlington amplifiers by providing lower base-emitter and collector-base capacitances are presented. The matrix amplifier has a 9.5 dB nominal gain and a 3-dB bandwidth to 24 GHz. This result benchmarks the highest bandwidth reported for an HBT distributed amplifier. The input and output VSWRs are less than 1.5:1 and 2.0:1, respectively. The total power consumed is less than 60 mW. The chip size measures 2.5*2.6 mm/sup 2/. The 2-stage Darlington amplifier has 7 dB gain and 3-dB bandwidth beyond 20 GHz. The input and output VSWRs are less than 1.5:1 and 2.3:1, respectively. This amplifier consumes 380 mW of power and has a chip size of 1.66*1.05 mm/sup 2/. >

GaAs heterojunction bipolar transistor MMIC DC to 10 GHz direct-coupled feedback amplifier

A DC-to-10-GHz fixed-gain amplifier implemented with a GaAs heterojunction bipolar transistor (HBT) monolithic microwave integrated circuit (MMIC) technology is described. The wideband amplifier design is based on Darlington-connected transistors with resistive feedback. A 3- mu m-emitter self-aligned-base ohmic metal HBT IC process (f/sub max/ approximately=30-40 GHz) with a simplified MBE growth structure is used to fabricate the amplifier. The feedback amplifier exhibits a flat 11-dB gain response to 6 GHz with a -3-dB roll-off at 10 GHz, 5-6-dB noise figure over the 10-GHz band, and 1-dB power compression of 11 dBm at midband. Compared to similar 0.5- mu m-gate GaAs MESFET wideband amplifiers, the HBTs third-order intercept point (IP3)/DC power ratio is two times greater and the chip size seven times smaller. Compared to similar advanced silicon bipolar and previously reported HBT direct-coupled amplifier designs, the GaAs HBT amplifier reported has twice the bandwidth.<<ETX>>

A 6-21-GHz monolithic HEMT 2*3 matrix distributed amplifier

The results of the first monolithic matrix distributed amplifier fabricated using pseudomorphic high-electron-mobility transistor (HEMT) technology are reported. The HEMT matrix amplifier obtains a combination of high gain, wide bandwidth, and reasonable IP3 and noise figure. The best gain response is 20 dB from 6 to 21 GHz. The noise figure is 5.5 dB and the third-order intercept point is 21 dBm. In comparison to GaAs HBT and MESFET technologies, the HEMT matrix distributed amplifier shows the best promise for wideband millimeter-wave applications. >

GaAs HBT MMIC broadband amplifiers from DC to 20 GHz

Three monolithic wideband and high-gain amplifiers implemented with 2-3- mu m GaAs heterojunction bipolar transistor (HBT) monolithic microwave IC (MMIC) technology are presented. A single-stage direct-coupled amplifier achieves a 3-dB bandwidth from DC to 20 GHz, which is believed to be the widest bandwidth reported for direct-coupled amplifiers. The amplifier has a 6-dB nominal gain with a peak gain of 7.3 dB at 10 GHz. The 1-dB compression is 10 dBm at midband, and the noise figure is between 7 and 10 dB over the bandwidth. A two-stage version of this amplifier achieves 14.5-dB gain up to 12 GHz. Its output power and noise performance are comparable to the single-stage version. The third wideband amplifier design is based on passive component and microstrip matching circuitry. The matched amplifier has 14.5-dB nominal gain with a 3-dB bandwidth from 5 to 12 GHz.<<ETX>>

GaAs HBT wideband and low power consumption amplifiers to 24 GHz

The authors report on the design and performance of a 2-24-GHz distributed matrix amplifier and a 1-20-GHz two-stage Darlington coupled amplifier based on an advanced HBT (heterojunction bipolar transistor) MBE (molecular beam epitaxy) profile which increased the bandwidth response of the distributed and Darlington amplifiers by providing lower base-emitter and collector-base capacitances. The matrix amplifiers have 9.5-dB nominal gain and a 3-dB bandwidth to 24 G-Hz. It is the highest bandwidth reported for an HBT distributed amplifier. The input and output VSWRs (voltage standing wave ratios) are less than 1.5:1 and 2.0:1, respectively. The total power consumed is less than 60 mW. The chip size measures 2.5*2.5 mm. The two-stage Darlington amplifier has 7-dB gain and 3-dB bandwidth to 20 GHz. The input and output VSWRs are less than 1.5:1 and 2.3:1, respectively. This amplifier consumes 380 mW of power and has a chip size of 1.66*1.05 mm.<<ETX>>

Monolithic regulated self-biased HEMT MMIC's

This work benchmarks the first demonstration of a monolithic HEMT IC design which incorporates active regulated self-bias. The HEMT current regulator design consists of integrating an op-amp in a feedback configuration with the LNA to achieve gain, noise figure, and DC bias performance which is tolerant to threshold variations due to the HEMT process. The HEMT LNA bias current can be maintained to within /spl plusmn/3% variation over a process threshold variation (V,,) of /spl plusmn/0.5 V. The bias circuitry regulates the bias current to within 1.5% over a 100/spl deg/C temperature range. The amplifier has a nominal gain of 10 dB and a noise figure of 2.5 dB over a 1-10 GHz bandwidth. Across several wafers with a threshold voltage spread of 0.5 V, the regulated LNA maintains repeatable gain and noise figure which varies by less than 1 and 0.75 dB, respectively. The monolithic regulated self-bias technique can be integrated with other HEMT MMICs in order to improve the performance and reliability, as well as to reduce the cost and weight of Integrated Microwave Assemblies (IMAs). >

A monolithic HEMT regulated self-biased LNA

This work benchmarks the first demonstration of a monolithic HEMT LNA design which incorporates active regulated self-bias. The HEMT LNA bias current can be maintained to within /spl plusmn/3% variation over a process threshold variation (Vgs) of /spl plusmn/0.5 Volt. The bias circuitry regulates the bias current to within 1.5% over a 100/spl deg/C temperature range. The amplifier has a nominal gain of 10 dB and a noise figure of 2.5 dB over a 1-10 GHz bandwidth. Across several wafers with a threshold voltage spread of 0.5 Volts, the active bias-regulated LNA maintains repeatable gain and noise figure which varies by less than 1 dB and 0.75 dB respectively. This monolithic regulated self-biased LNA demonstration sheds new light on the producibility and reliability of HEMT MMICs and their applications.<<ETX>>

A novel compact monolithic active regulated self-biased InP HEMT amplifier

This letter reports on the first results of a monolithic active regulated self-biased HEMT amplifier fabricated in InP technology. The self-bias scheme incorporates an op-amp-based HEMT regulator topology that regulates the bias current to within 6% over a threshold variation of /spl plusmn/0.2 V. The DC yield based on this performance criteria was 75% across a wafer. The InP HEMT amplifier achieves an RF gain of 10-dB and a 3-dB bandwidth of 1-14 GHz. Across a wafer with a total threshold variation of 0.4 V, the gain variation was maintained to less than /spl plusmn/1 db. The compact integrated HEMT regulated amplifier circuit was realized using area-efficient analog design techniques that consumed less than 1.3/spl times/1.1 mm/sup 2/. This demonstration has far-reaching implications to the producibility and reliability of InP HEMT MMICs.<<ETX>>

A Low Cost Packaging/Testing Procedure for Manufacturing GaAs MMIC

The development of a low cost, high throughput testing/packaging procedure for GaAs MMIC is described. Automated on-wafer RF and DC testing is essential for volume production of MMIC chips. However, most MMIC circuits cannot be tested at wafer level due to lack of proper RF test environment. The proposed frame tape chip carrier approach takes full advantage of the RF probe system. This technique reduces the high cost of RF package measurements and reliability testing. The measurement and packaging is demonstrated on several MMIC chips. It can easily be automated for high volume production.