A circuit that receives a series a digital signal values from a digital circuit output where the output has a propensity to produce digital values with a metastable error. The circuit produces an analog output signal having values over time corresponding to the digital signal values. The circuit includes two data paths that receive the digital signal values and produce a delayed analog signal. One data path includes an analog delay and the other data path includes a digital delay and a digital to analog converter. The circuit uses the output of the two data paths to adjust a later output analog signal value that is produced by the analog circuit output subsequent to a former output analog signal value produced by the analog circuit output that corresponds to a digital signal value of the series with a metastable error to compensate for the metastable error in the output signal.

A correction method and a correction circuit for a sigma-delta modulator (SDM) are provided. The SDM includes a loop filter, a quantizer, and a digital-to-analog converter (DAC). The correction method includes the following steps: controlling the DAC not to receive the output of the quantizer; controlling the SDM to stop receiving signals; inputting a test signal to the DAC; converting the output of the loop filter to a digital signal; comparing the digital signal with a preset value; and adjusting the loop filter according to the result of comparing the digital signal and the preset value.

A method includes using a first feedback loop to compensate for a first excess loop delay (ELD) associated with a first quantizer and a first DAC of the first feedback loop. The first quantizer provides a first quantizer output to a second feedback loop. A second feedback loop compensates for a second ELD associated a second quantizer and a second DAC of the second feedback loop. The second quantizer reduces a metastability error associated with the first quantizer output.

A correction method and a correction circuit for a sigma-delta modulator (SDM) are provided. The SDM includes a loop filter, a quantizer, and a digital-to-analog converter (DAC). The correction method includes: generating a test signal for a frequency to be tested; inputting the test signal to a feedforward circuit that includes at least one adjustable impedance circuit, the test signal being inputted to the SDM through the impedance circuit; calculating an output signal of the SDM to obtain a value of a signal transfer function (STF) of the SDM at the frequency to be tested; and adjusting the impedance circuit.

A correction method and a correction circuit for a sigma-delta modulator (SDM) are provided. The SDM includes a loop filter, a quantizer, and a digital-to-analog converter (DAC). The correction method includes: generating a test signal for a frequency to be tested; inputting the test signal to a feedforward circuit that includes at least one adjustable impedance circuit, the test signal being inputted to the SDM through the impedance circuit; calculating an output signal of the SDM to obtain a value of a signal transfer function (STF) of the SDM at the frequency to be tested; and adjusting the impedance circuit.

An apparatus for a signal processor for Wide-Band Applications is provided. The signal processor includes a plurality of parallel branches. Each parallel branch includes a frequency shifter, a sigma-delta-modulator, and a filter. The output signal of each branch is combined via a signal recombiner. The signal processor is suitable for wide-band applications due to centering the zeros of the sigma-delta-modulator's noise transfer function and filter's noise transfer function at the frequency of the frequency shifter in the same branch of the signal processor. Centering these zeros at the frequency of the frequency shifter shapes the quantization noise added by the sigma-delta-modulator away from the input signal frequency to make it easier to remove the quantization noise. This wideband performance is also achieved due to the design of the embodiment's filters. The embodiments of this invention use filters with symmetric transition bands and a pass-band that is wide enough for use in wireless applications.

A correction method and a correction circuit for a sigma-delta modulator (SDM) are provided. The SDM includes a loop filter, a quantizer, and a digital-to-analog converter (DAC). The correction method includes the following steps: controlling the DAC not to receive the output of the quantizer; controlling the SDM to stop receiving signals; inputting a test signal to the DAC; converting the output of the loop filter to a digital signal; comparing the digital signal with a preset value; and adjusting the loop filter according to the result of comparing the digital signal and the preset value.

A multichannel transmit and/or receive system, each channel includes a DAC and a sigma-delta modulator the transfer function of which is expressed thus:

OUT(z)=IN(z).Math.FTS(z)+Q(z).Math.FTB(z),

where OUT is the output signal of the sigma-delta modulator, IN is the input signal of the sigma-delta modulator, FTS is the transfer function of the input signal, Q is the quantization noise and FTB is the transfer function of the quantization noise, the second terms of the transfer function of the sigma-delta modulator only being distinct from one another for two channels Vi, Vj, in order to decorrelate the quantization noise of distinct channels, the first term of said transfer function for channel Vi being equal to the first term of said transfer function for channel Vj.

A circuit that receives a series a digital signal values from a digital circuit output where the output has a propensity to produce digital values with a metastable error. The circuit produces an analog output signal having values over time corresponding to the digital signal values. The circuit includes two data paths that receive the digital signal values and produce a delayed analog signal. One data path includes an analog delay and the other data path includes a digital delay and a digital to analog converter. The circuit uses the output of the two data paths to adjust a later output analog signal value that is produced by the analog circuit output subsequent to a former output analog signal value produced by the analog circuit output that corresponds to a digital signal value of the series with a metastable error to compensate for the metastable error in the output signal.

An adapter, for coupling a first medical instrument to a control console having a console receptacle configured for attachment thereto of a different second medical instrument, includes a case, a receptacle, circuitry contained in the case and an output connector. The receptacle is configured to receive an input connector of the first medical instrument conveying modulated analog input signals from the first medical instrument. The circuitry includes an analog/digital converter coupled to sample and digitize the analog input signals to generate digital samples, digital processing circuitry configured to digitally downconvert the digital samples so as to generate a baseband digital signal, and a digital/analog converter configured to convert the baseband digital signal to an analog baseband signal compatible with an output of the second medical instrument. The output connector is configured to be inserted into the console receptacle and to convey the analog baseband signal to the console.