Pulse quadrature modulator and method

Abstract

A pulse quadrature modulator generates both alpha and beta binary signals, each one serial bit switched at an RF carrier frequency at a fraction of a high speed quantization clock. The alpha and beta binary signals each have respective alpha and beta pulse edges nominally occurring at two times the RF carrier frequency. The alpha and beta pulse edges alternate respectively. The alpha and beta pulse edges are each synchronized to the high speed quantization clock switched based on the baseband I and Q signal inputs. First and second switches gate a power signal using a respective of the alpha or beta binary signals to respectively produce first and second power outputs. The first and second switches differentially drive an RF load such as an antenna across the first and second power outputs having pulse edges at nominally at an integer multiple of four times the RF carrier frequency.

Description

BACKGROUND OF THE INVENTIONS1. Technical Field[0001]The present inventions relate to a quadrature modulated bridge switching power stage that produces a modulated RF signal and, more particularly, relate to a pulse modulated bridge power stage for creating a quadrature modulated RF signal for RF transmission.2. Description of the Related Art[0002]Quadrature modulation is a method of transmitting a complex baseband signal using a single RF (radio frequency) frequency and an RF power amplifier. The power conversion efficiency of the RF power amplifier is a function of the RF signal envelope peak to average ratio. The power conversion efficiency can be as low as 10% for large peak to average ratio (10 dB). Even for an FM signal which is constant envelope with a peak to average ratio of 0 dB the power conversion efficiency is only about 50%. The remaining power is lost as heat and results in higher power consumption as well as cost and size of a system to eliminate the heat. There is al...

AI Technical Summary

Benefits of technology

The patent text is discussing a solution to reduce the cost of RF transmission by eliminating the use of a linear RF amplifier and replacing it with a switching RF stage. The switching RF stage creates an amplified modulated signal with high power, efficiency, and fidelity, while also improving power conversion efficiency. This solution results in significant cost savings and improved performance. As semiconductor processes improve, more RF systems can be implemented using this invention.

Problems solved by technology

Power consumption, directly or indirectly, contributes to a large portion of the cost of RF transmission.

Even when the cost of the power consumed is low there is significant cost associated with elimination of the heat from a linear RF amplifier.

Further, the speed of digital circuits continues to go up and their cost continues to go down.

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