Development of a 4-Bit Parallel Analog-To-Digital Converter and a Four-Quadrant Double-Balanced Mixer Using Heterojunction Bipolar Transistor Technology.

摘要

A 4-bit parallel analog-to-digital converter (ADC) and a four-quadrant double-balanced mixer were designed and simulated using heterojunction bipolar transistor (HBT) technology to test the dc and high-frequency characteristics of HBTs. HSPICE simulations of small-scale components and the large-scale ADC operated within expected ranges. The ADC implemented with the Rockwell HBT model operated at a sampling rate of over 1 GHz, and the Fellows model also operated at a 1 GHz sampling rate. The mixer produced an intermediate frequency (IF) signal using radio frequency (RF) and local oscillator (LO) inputs. The circuit produced a +9 dB power gain with less than one percent harmonic distortion and shows potential for microwave applications. In order to facilitate the fabrication of HBT circuits, a Magic technology file was developed to lay out HBTs and extract the transistors for the purpose of doing a layout sus schematic check. The extraction software was altered to recognize HBTs in the extracted file. The program ext2spice successfully identified HBTs and converted the transistors, as well as parasitic capacitances, into an HSPICE netlist. Since load resistors determine the output logic swing in current-mode logic, an attempt was made to extract resistors using the HBT technology file for Magic. The configuration of the HBT within Magic and the methods used for resistance extraction offer ways to extract HSPICE netlists for accurate simulations. HBT, Heterojunction bipolar transistor, GaAs, Analog-to-digital conversion, Mixers, Extraction.