A monolithic low-cost 1 mm(2) balanced BPSK modulator employing cold HBTs and scaled-down couplers at 38 GHz

The design and performance of a 38 GHz MMIC biphase amplitude modulator emp loying cold HBTs as switching elements are presented. Direct carrier modula tion together with a balancing topology are employed to lower the circuit's complexity and cost, and to remove the amplitude and phase errors that occ ur at higher frequencies. Furthermore, by using a miniature microstrip coup ler, the total area of the chip is reduced to 1 mm(2). It is found that thi s technique is very robust, producing excellent performances at millimeter- wave frequencies. (C) 2000 John Wiley & Sons, Inc.