Rick Hudgens

5 W monolithic HBT amplifier for broadband X-band applications

The first monolithic heterojunction bipolar transistor (HBT) amplifier producing greater than 5-W output power at X-band frequencies is reported. Monolithic impedance-matching circuits were designed using measured and modeled large-signal device parameters at the unit-cell level. Unit cells were then connected in parallel to obtain an output-power increase proportional to unit-cell count. A single-stage, totally monolithic amplifier was fabricated using 2.4-mm-emitter-length AlGaAs-GaAs HBT for operation in the 7-10-GHz frequency range. A maximum of 5.3-W CW output power was obtained in this frequency range with 4.6-dB gain and 22% power-added efficiency.<<ETX>>

2.5 W CW X-band heterojunction bipolar transistor

A 2.43-W CW (continuous wave) output power was obtained with AlGaAs-GaAs heterojunction bipolar transistors at 10 GHz with 5.8-dB gain and 30% power-added efficiency using 2- mu m minimum-geometry devices. The device design and fabrication techniques were improved to maintain high power density (>3 W/mm of emitter length) operation as the device size is increased. Accurate device models were developed both for common-emitter and common-base devices to aid in this size scaling.<<ETX>>

High power and high efficiency monolithic HBT VCO circuit

A description is given of the design, fabrication, and performance of the first reported monolithic voltage-controlled oscillator (VCO) using a heterojunction bipolar transistor (HBT) as the active device and an integrated p-n junction diode as the varactor. The monolithic VCO employs a self-aligned AlGaAs-GaAs HBT with ten emitter fingers (2.5 mu m*20 mu m each) whose maximum frequency of oscillation (f/sub max/) is 60 GHz. A continuous tuning bandwidth of 10.78-13.04 GHz (19%) was achieved with an output power of 219 mW and a DC-to-RF conversion efficiency of 31%. Maximum output power of 277 mW and 30% efficiency was also demonstrated at somewhat lower tuning bandwidths (11.00-11.88 GHz). The effects of bias voltage and current variations on the performance of the VCO have been studied. The single sideband FM noise of the free-running VCO was measured to be -55 dBc/Hz at 10 kHz offset and -75 dBc/Hz at 100 kHz offset from the carrier (11.26 GHz). These results indicate that HBT can be a viable broadband microwave source for high-power, low-phase-noise system applications.<<ETX>>

Monolithic X-band heterojunction bipolar transistor power amplifiers

Compact, single-stage HBT power amplifiers with on-chip impedance matching and bias circuits were fabricated on MOCVD-grown wafers in two circuit designs. The first design produced 1.0-W CW output power at 9 GHz with 5.8-dB gain and 40% power-added efficiency. The size of this monolithic chip was 1.9 mm*0.7 mm. The second (larger) amplifier design produced 2.5-W CW output power at 8 GHz with 6.1-dB gain and 39% power-added efficiency. The size of this amplifier chip was 1.9 mm*1.7 mm. Each amplifier had about 10% gain bandwidth. An output power of 5.3 W CW was obtained by parallel connection of two monolithic chips with 4.3-dB gain and 33% power-added efficiency. The high power density (>2.0 W/mm of emitter length) of HBTs (heterojunction bipolar transistors), together with the monolithic implementation of lumped element matching circuits, resulted in significant reduction of amplifier chip size in both designs.<<ETX>>

Ku-band monolithic 7-watt power amplifier using AlGaAs/GaAs 0.25- mu m T-gate heterostructure FET technology

Two advanced Ku-band MMIC (monolithic microwave integrated circuit) power amplifiers have demonstrated state-of-the-art performance at upper Ku-band. One design delivers 7.2 W CW (continuous wave) and 9.3 W pulse at 25% power-added efficiency (PAE). The other design delivers 32% PAE at 2.7 W CW. Electromagnetic simulator (Sonnet EM) analysis contributed to the successful design of both circuits. A narrow 3-W, 30%-efficient, Ku-band MMIC is ready for phased-array radar T/R (transmit/receive) module applications. Power combining two of the 7-W MMICs has delivered 15.7 W (pulsed) in a small, simple 13-mm*18-mm assembly.<<ETX>>

Replacing Error Vector Magnitude Test with RF and Analog BISTs

RF and analog BIST techniques are capable of replacing the traditional error vector magnitude (EVM) test used in production. In a case study, four BISTs detected actual production faults in a commercial, highly integrated WLAN device. In combination with traditional digital testing, the BISTs caught an impressive 100% of EVM failures during production of over a million devices, which presents significant opportunities for both cost and time savings.

A novel RF phase error Built-in-Self-Test for GSM

This paper discusses a novel RF Built-in-Self-Test (RF-BiST) targeting to replace the traditionally expensive and time-consuming RF parametric phase error test on a GSM/EDGE Digital Radio Processor (DRP) radio transceiver. The verification of the RF BiST in a production environment and a comparison of the internal BiST vs. the current test in are presented, which validates the RF BiST as an accepted test method for determining the phase error of GSM devices. The results illustrate that there are great opportunities in reduction of test time and costs by moving to the internal digital method of BiST for testing RF/analog IC products.

Comparison of self-aligned and non-self-aligned GaAs E/D MESFETs

The device characteristics and circuit performance of self-aligned GaAs E/D-MESFETs have been compared. The fabrication process for both devices is discussed. Electrical measurements across a 2-in wafer showed that an average self-aligned 40- mu m-wide, 1- mu m-long enhancement device has transconductance of 275+or-17 mS/mm, an intrinsic K-value of 16.3+or-2.7 mS/V, a series resistance of 0.88+or-0.1 Omega -mm, and a threshold deviation of 28 mV. Corresponding data for the non-self-aligned devices were 191+or-19 mS/mm, 10.3+or-1.4 mS/V, 1.2+or-0.2 Omega -mm, and 45 mV, respectively. An ECL-compatible 1-kb static RAM and a 4-kb static RAM were fabricated using both self-aligned and non-self-aligned processes for comparison. Using the self-aligned process, the power consumption of the 1-kb SRAM was 230 mW, compared to 530 mW for the non-self-aligned SRAM, while access times remained the same. Typical access times for self-aligned 4-b SRAM devices ranged from a minimum of 2.8 ns to a maximum of 3.8 ns. This 1-ns range is considerably less than that of a typical non-self-aligned device with 2.5 ns of access time scatter. >

Methodology to Replace Sensitivity BER and Transmit Power Production Tests in Bluetooth Devices with BiSTs

Production testing of Bluetooth (BT) devices is challenging due to the complex nature of the RF tests that have to be performed to verify functionality. In this paper we detail Built-in Self Tests (BiSTs) that can be used to replace these complex and expensive functional tests. We also present the data from our analysis of over 1 million production units. With sufficient margin to specification, we can eliminate functional tests and implement BiSTs that are faster, cheaper and provide better coverage while guaranteeing acceptable Defective Parts Per Million (DPPM) numbers. These BiSTs along with traditional digital tests can completely replace traditional Bluetooth RF tests like Bit Error Rate (BER) and Transmitted (TX) Power.

Maximizing Parallel Testing in an FM Receiver

High volume production environments create great challenges for production testing and verification of Radio Frequency (RF) devices. In this environment, much emphasis is put on parallel testing, or the ability to test multiple devices at the same time using a single tester. In order for this parallelism to become a reality, there is a need for production RF tests to be simplified and reduced to requiring only the simplest test stimulus and analysis. In this paper, we present a new method of measuring the performance of a Frequency Modulation (FM) receiver that requires only a continuous wave signal input in order to eliminate the more costly Signal-to-Noise Ratio test. Using this new technique we will then demonstrate how simplifying this test and adding frequency diversity enables testing of up to 8 devices in parallel using a single tester.