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Применения > > An IQ Demodulator-Based IF-to-Baseband Receiver with IF and Baseband Variable Gain and Programmable Baseband Filtering

An IQ Demodulator-Based IF-to-Baseband Receiver with IF and Baseband Variable Gain and Programmable Baseband Filtering (CN0248)

This circuit is a flexible, frequency agile IF-to-baseband receiver. Variable gain at both IF and baseband is used to adjust the signal level. The ADRF6510 baseband ADC driver also includes a programmable low-pass filter that eliminates out-of-channel blockers and noise.


The bandwidth of this filter can be dynamically adjusted as the bandwidth of the input signal changes. This ensures that the available dynamic range of the ADC that this circuit drives is fully used.


The core of the circuit is an IQ demodulator. The 2×LO based phase-splitting architecture of the ADL5387 allows for operation over a wide frequency range. Precise quadrature balance and low output dc offsets ensure that there is minimal degradation of the error vector magnitude (EVM).


The interfaces between all of the components in this circuit are fully differential. Where dc coupling is required between stages, the bias levels of the adjacent stages are compatible with each other.



Figure 1. Direct Conversion Receiver Simplified Schematic (All Connections and Decoupling Not Shown)

Возможности

  • IF-to-based receiver
  • 30MHz to 2GHZ quadrature demodulation
  • Low EVM

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