Measurements of TlBaCaCuO‐based dc superconducting quantum interference devices (SQUIDs) performed using a practical feedback circuit gave a flat frequency response and an energy sensitivity of 6×10−30J/Hz at 5 kHz and 77 K with an 80 pH SQUID. Flux‐locked loop operation was demonstrated to be strongly effective in eliminating the magnetic field hysteresis of the SQUID. The SQUIDs were operated in the flux‐locked loop at temperatures over 90 K and the 1/fnoise was found to decrease with increasing temperature near 77 K.