This paper describes the design, analysis and test results for a 4-bit pseudo-random bit-sequence generator (PRBSG) implemented with complementary output switching logic (COSL) gates. The PRBSG was optimized using a Monte Carlo simulation method for 10-GHz operation. The circuit has been fabricated using niobium technology with critical current density of 1 kA/cm/sup 2/ and sheet resistance of 1 /spl Omega//sq. The 4-bit PRBSG consists of 12 gates and its area is 1530/spl times/950 /spl mu/m/sup 2/. It has been fully tested with a three-phase power supply, and its power consumption is 0.15 mW. The correct operations have been verified experimentally at clock frequencies of up to 2 GHz.