  Kinetic inductance traveling-wave parametric amplifiers (KI-TWPA) have a wide
instantaneous bandwidth with near quantum-limited performance and a relatively
high dynamic range. Because of this, they are suitable readout devices for
cryogenic detectors and superconducting qubits and have a variety of
applications in quantum sensing. This work discusses the design, fabrication,
and performance of a KI-TWPA based on four-wave mixing in a NbTiN microstrip
transmission line. This device amplifies a signal band from 4 to 8~GHz without
contamination from image tones, which are produced in a separate higher
frequency band. The 4 - 8~GHz band is commonly used to read out cryogenic
detectors, such as microwave kinetic inductance detectors (MKIDs) and Josephson
junction-based qubits. We report a measured maximum gain of over 20 dB using
four-wave mixing with a 1-dB gain compression point of -58 dBm at 15 dB of gain
over that band. The bandwidth and peak gain are tunable by adjusting the
pump-tone frequency and power. Using a Y-factor method, we measure an
amplifier-added noise of $ 0.5 \leq N_{added} \leq 1.5$ photons from 4.5 - 8
GHz.
