This paper describes a sub-sampling delta modulator operating at giga Hertz range to capture radio frequency signals. Down-conversion to low-IF is achieved by sub-sampling with a 1-bit quantizer. It presents higher bandwidth and SNR than those of the state-of-the-art sub-sampling modulators. Input carrier frequency can be followed over a wide range by controlling the sampling rate. Center frequency of the band-pass filters, which is placed at IF, is independent of input carrier frequency. A SNR higher than 55 dB is expected for a 2 MHz bandwidth signal modulated at 2-GHz frequency when the sampling rate is set to 990 mega samples per second