  We describe a wide-band Josephson Parametric Amplifier (JPA) that is
impedance-matched using an integrated compact superconducting transmission line
transformer. The impedance transformer consists of two broadside coupled
transmission lines configured in a Ruthroff topology which enables a wide
matching bandwidth from 2 to 18 GHz, reducing the input line impedance and the
device resonance quality factor by a factor of 4. This enables gain flatness
and flexibility in the choice of the amplifier's tuning range. The amplifier
has up to 20dB gain, with less than 1 dB of ripple, 2-3 GHz gain-bandwidth
product and -126 dBm input 1-dB compression point. Moreover, the device active
area fits into a 1mm x 1mm space, thus easing integration into large quantum
systems.
