Demonstration circuit 2664A is a VCO Rider Board with Loop Filter that supports the popular 0.5" × 0.5" VCO package footprint.
The DC2664A expedites evaluation of Phase-Locked Loop (PLL) devices requiring an external Voltage Controlled Oscillator (VCO). Without the DC2664A, each VCO and PLL combination requires a unique loop filter design, resulting in several PLL demo board modifications to evaluate each VCO. These board modifications are time consuming and often result in damage to either the PLL or the VCO.
The DC2664A integrates the VCO and loop filter allowing these unique designs to reside on multiple DC2664As. The DC2664A RFOUT and VTUNE SMA connections allow the user to quickly evaluate a PLL with multiple VCOs without risk of damage from multiple board modifications.
VCOs are notoriously sensitive to power supply noise and spurs. The DC2664A resolves the concern of locating a low noise and low spurious lab supply by powering the VCO with an onboard ultralow noise and ultrahigh PSRR LDO, the LT3042. A second LT3042 LDO is available on the DC2664A to power an active loop filter. Both LDOs are powered from a single supply, simplifying the number of lab supplies required to evaluate a VCO and PLL combination.
The DC2664A was designed to mate directly with the LTC6955 (DC2611A) and LTC6952 (DC2609A) demo boards.