Gain compensation in an ultra-wideband transceiver
First Claim
1. A circuit for providing gain compensation of a swept frequency response in an ultra-wideband system, the circuit comprising:
- a multiplier receiving a first input signal comprising a fixed-level intermediate frequency (IF) signal and a second input signal comprising a gain control signal, the multiplier providing a variable amplitude IF signal output;
a mixer coupled to the multiplier signal output, the mixer producing a variable amplitude ultra-wideband output signal derived from the variable amplitude IF signal and a swept frequency signal;
a digital-to-analog converter providing the gain control signal to the multiplier; and
a memory containing gain values, the gain values controlling the digital-to-analog converter, wherein the gain values compensate for amplitude variations of a swept frequency response of the ultra-wideband system.
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Accused Products
Abstract
A circuit for providing gain compensation to a swept frequency response in an ultra-wideband system includes using a variable amplitude IF signal into a gigahertz mixer to control the amplitude of a ultra-wideband transmitter. The variable amplitude IF signal is generated by a multiplier receiving a fixed-level intermediate frequency (IF) signal and a gain control input. The gain control input being provided by an digital-to-analog converter controlled by gain control values in a look-up table. The values of the look-up table are generated by inverting, normalizing, and scaling the uncompensated gain response of the ultra-wideband system. The gain compensated system produces a substantially flat amplitude response at the output of a quadrature receiver.
21 Citations
22 Claims
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1. A circuit for providing gain compensation of a swept frequency response in an ultra-wideband system, the circuit comprising:
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a multiplier receiving a first input signal comprising a fixed-level intermediate frequency (IF) signal and a second input signal comprising a gain control signal, the multiplier providing a variable amplitude IF signal output; a mixer coupled to the multiplier signal output, the mixer producing a variable amplitude ultra-wideband output signal derived from the variable amplitude IF signal and a swept frequency signal; a digital-to-analog converter providing the gain control signal to the multiplier; and a memory containing gain values, the gain values controlling the digital-to-analog converter, wherein the gain values compensate for amplitude variations of a swept frequency response of the ultra-wideband system. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A system for scanning an individual using an ultra-wideband transceiver, the system comprising:
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a transmit and receive antenna array, the antenna array emitting a gain compensated ultra-wideband sweep signal from a transmit element and receiving a reflected signal on a corresponding receive element; an ultra-wideband transmitter chain comprising an ultra-wideband frequency source, a controllable amplitude intermediate frequency (IF) source, and a mixer which outputs the gain compensated ultra-wideband sweep signal; an ultra-wideband receiver chain, the receiver chain comprising a low noise amplifier, a downconverter, and a quadrature receiver; wherein the gain compensated ultra-wideband sweep signal is derived by varying the controllable amplitude IF source into the mixer, and wherein the gain compensated ultra-wideband sweep signal compensates for frequency response amplitude variations across a frequency sweep of the system such that a substantially uniform amplitude signal at an output of the quadrature receiver is acquired if a flat target is presented to the antenna array. - View Dependent Claims (9, 10, 11, 12, 13, 14, 20)
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15. A method of controlling an ultra-wideband transceiver in a system which determines physical measurements of an individual, the method comprising:
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selecting a transmit and receive element pair of the antenna array; initiating a frequency sweep of an individual via a transmit antenna array, the sweep comprising emission of a gain compensated ultra-wideband transmit signal generated using a variable amplitude intermediate frequency (IF) signal mixed with a fixed amplitude ultra-wideband sweep signal; receiving and downconverting a signal reflected off of the individual; demodulating the downconverted signal; wherein the gain compensated ultra-wideband transmit signal compensates for frequency response amplitude variations across the frequency sweep of the system such that a substantially uniform amplitude signal measured at the demodulated signal. - View Dependent Claims (16, 17, 18, 19)
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21. A method of calibrating an ultra-wideband transceiver for a uniform gain response in a system which determines physical measurements of an individual, the method comprising:
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setting a gain control table to a fixed value, wherein the gain control table is used to control the gain of an intermediate frequency signal into a mixer whose output generates an ultra-wideband frequency sweep; transmitting the ultra-wideband frequency sweep through the system, the system having a flat target; measuring and recording demodulated output signal levels over the sweep, wherein a plurality of sweeps are transmitted, measured and recorded; averaging the demodulated output signal levels for a plurality of frequencies over the plurality of sweeps to obtain average values for each of the plurality of frequencies; inverting the average values to compute gain control values; normalizing the gain control values; and loading the normalized values in the gain control table, wherein the normalized values provide gain compensation to the intermediate frequency signal into the mixer, whereby a gain compensated ultra-wideband sweep signal is produced. - View Dependent Claims (22)
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Specification