RF frequency multipliers are nonlinear devices that produce an output signal with a frequency that is larger than the frequency of a corresponding input signal by a predetermined factor. RF frequency multipliers operate over a specific input frequency range and are able to suppress or reduce unwanted harmonics from the output signal. There are two basic types of devices: active and passive. Active RF multipliers produce an output signal with a power level that is larger than that of the input signal. The power level difference between the output signal and the input signal is called conversion gain, an amount that is measured in decibels (dB) and expressed as a positive number. Passive RF multipliers produce an output signal with a power level that is smaller than that of the input signal. The difference in power levels between the output signal and the input signal is called conversion loss, an amount that is expressed in decibels. Conversion loss is a negative number, but usually specified as an absolute value.
Performance specifications for RF frequency multipliers include multiplying factor, input power, output power and spurious rejection. Frequency doublers, triplers, quadruplers and quintuplers are commonly available. Input power is the amount of RF power that must be applied to a device in order to multiply the frequency of the input signal. It is also the specified power range for the conversion loss. Both output power and input power are expressed in decibels relative to one milliwatt (dBm). Spurious rejection is the difference between the desired output harmonic and any other harmonic as viewed at the RF multiplier’s output. It is usually expressed as a positive ratio in decibels relative to the carrier power (dBc).
There are several mounting styles for RF frequency multipliers. Surface mount technology (SMT) adds components to a printed circuit board (PCB) by soldering component leads or terminals to the top surface of the board. Through hole technology (THT) mounts components by inserting component leads through holes in the board and then soldering the leads in place on the opposite side of the board. Flat pack (FPAK) devices have flat leads and are available in a variety of body sizes and pin counts. Connectorized devices attach with coaxial or other types of connectors. Waveguide assemblies consist of a hollow metallic conductor with a rectangular or elliptical cross-section. Some conductors contain solid or gaseous dielectric materials.
RF frequency multipliers use several types of connectors. Bayonet Neil-Concelman (BNC) connectors are used in applications to 2 GHz. Threaded Neil-Concelman (TNC) connectors are similar in size to BNC connectors, but feature a threaded coupling nut for applications that require performance to 11 GHz. Miniature coaxial (MCX) connectors provide broadband capability through 6 GHz and are used in applications where weight and physical space are limited. Ultra high frequency (UHF) connectors are designed with non-constant impedance for use in comparatively low voltage and low frequency applications. Subminiature-A (SMA) connectors directly interface the cable dielectric without air gaps. Subminiature-B (SMB) connectors snap into place and are used for frequencies from DC to 4 GHz. Subminiature-P (SMP) connectors are rated to 40 GHz and, depending on detent type, can withstand from 100 to 100,000 interconnect cycles. Other connectors for RF frequency multipliers include MMCX, Mini-UHF, Type F, Type N, 1.6/5.6, and 7-16 connectors.