James W Summers

US Patent:

43552897, Oct 19, 1982

Filed:

Jul 14, 1980

Appl. No.:

6/168502

Inventors:

James B. Beyer - Madison WI
James B. Summers - Spokane WA

Assignee:

Wisconsin Alumni Research Foundation - Madison WI

International Classification:

H03C 500
H04L 2720

US Classification:

332 17

Abstract:

A parallel type modulator is disclosed which utilizes a pair of bi-phase modulators (10), each of which are capable of independent phase and amplitude modulation. In each bi-phase modulator, a carrier frequency signal is split by a power splitter (20) into two signals 180. degree. apart in phase which are passed through directional couplers (30 and 31) and a pair of PIN diodes (35 and 36) to a summing junction (37). A bias source circuit (42) delivers biasing current to the coupled outputs of the directional couplers (30, 31) and through the PIN diodes (35, 36) to the summing junction (37); this current is returned to ground through a bias return circuit (44) which conducts the DC or low frequency biasing signal but allows the carrier frequency output signal to be passed through to the output of each bi-phase modulator. Reduction of the bias current to one diode below null levels at which the intermediate signals cancel will cause a carrier frequency signal to appear at the summing junction which will be in phase with the signal passed through the other diode. A continuous variation of the bias current through one of the diodes at a level below the null current level will result in amplitude modulation of the output signal at the summing junction.