Precision phase modulators utilizing cascaded amplitude modulators

• US 4,229,715 A
• Filed: 12/15/1978
• Issued: 10/21/1980
• Est. Priority Date: 12/15/1978
• Status: Expired due to Term

• Current Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Inventors: Henry, Paul S.
• Primary Examiner(s): Grimm, Siegfried H.
• Application Number:
  US05/969,775
• Time in Patent Office: 676 Days
• Field of Search: 332/16 R, 332/22, 332/23 R, 332/23 A, 332/18, 325/45, 325/47, 325/145
• US Class Current: 332/145
• CPC Class Codes: H03C 3/38 by converting amplitude modulation to angle modulation

Abstract

The present invention relates to a precision phase modulator wherein a carrier signal of constant amplitude and frequency and a modulating signal are applied to the two inputs of the first one of a cascade of linear suppressed-carrier amplitude modulators. Each subsequent modulator of the cascade arrangement concurrently modulates the output signal of the previous modulator of the cascade with the modulation signal. The input carrier signal and the output signal of each modulator of the cascade is tapped-off and weighted, the weighted carrier input and outputs of the even-numbered modulators and the weighted outputs of the odd-numbered modulators are separately added and are combined in quadrature to provide a phase modulated output signal.

Claims

1. A phase modulator comprising

a first and a second linear suppressed-carrier amplitude modulator, each modulator comprising a first and a second input terminal and an output terminal

characterized in that

the first and second modulators are connected in cascade with the output terminal of the first modulator connected to the first input terminal of the second modulator, and the first input terminal of the first modulator and the second input terminals of the first and second modulators are capable of receiving a carrier signal and a modulating signal, respectively;

the phase modulator further comprising

an adding means comprising a first and second input terminal coupled to the first input terminal of the first modulator and the output terminal of the second modulator, said adding means being capable of generating an output signal corresponding to the sum of the input signals;

a quadrature coupler capable of combining in quadrature the output signals from the adding means and the first modulator to provide a phase modulated output signal; and

a first, second and third weighting means capable of introducing a separate predetermined weighting factor to the signal being applied to the first and second input terminal of the adding means and the output signal from the first modulator being applied to the quadrature coupler, respectively.

2. A phase modulator comprising

a plurality of n linear suppressed-carrier amplitude modulators, each modulator comprising a first and a second input terminal and an output terminal

characterized in that

the plurality of n modulators are connected in a cascade arrangement with the output terminal of each modulator connected to the first input terminal of the next modulator in the cascade arrangement, and both the first terminal of the first modulator in the cascade arrangement and all second terminals of the plurality of n modulators are capable of receiving a carrier signal and a modulating signal, respectively;

the phase modulator further comprising

a first adding means comprising input terminals which are connected to the first input terminal of the first modulator of the cascade arrangement and the output terminals of the even-numbered modulators of the cascade arrangement, said first adding means being capable of generating an output signal corresponding to the sum of the input signals;

a second adding means comprising input terminals which are connected to the output terminals of the odd-numbered modulators of the cascade arrangement, the second adding means being capable of generating an output signal corresponding to the sum of the input signals;

a plurality of n+1 weighting means, each weighting means disposed in a separate one of the input connections to the first and second adding means and capable of introducing a separate predetermined weighting factor to a signal passing therethrough; and

a quadrature coupler capable of combining in quadrature the output signals from the first and second adding means to provide a phase modulated output signal.