Analog Devices has introduced a small USB-powered RF power amplifier that is optimized for 2400 MHz operation. The CN4017 evaluation board provides 20 dB of gain through its RF band of operation, boosting signals for various communication protocols such as ISM, MC-GSM, W-CDMA, TD-SCDMA, and LTE. It requires a 5 V USB supply for normal operation. The input and output, both populated with edge-mounted SMA connectors, are dc blocked and matched to 50 Ω for ease of use.
Most of the modern radio-link systems are capable of transmitting signals that have limited output power. Depending on the environment and signal power, the range of transmission varies. For a longer range of operations or environments with more RF interference, higher output power is required. The CN4017 is used to increase the magnitude of the power of transmitted signals to a level high enough to reach a given distance.
The EVAL-CN0417-EBZ board connects through SMA and is powered by the bus voltage from the USB port. It consists of:
- The ADL5606 is a broadband, two-stage, 1 W RF driver amplifier that operates over a frequency range of 1800 MHz to 2700 MHz. The device can be used in a wide variety of wired and wireless communication protocols, including ISM, MC-GSM, W-CDMA, TD-SCDMA, and LTE.
- The LTM8045 is an integrated switching DC/DC converter that contains a current-mode controller, a power switching element, a power coupled inductor, a power Schottky diode, and a modest amount of input and output capacitance. It can be configured as a SEPIC or inverting converter by simply grounding the appropriate output rail.
Impedance Matching
The RF input (Pin 1) and RF outputs (Pin 9 to Pin 12) of the ADL5606 can be matched to 50 Ω with at most one external component and the microstrip line used as an inductor. The recommended component values for ADL5606 matching are provided in the product data sheet for three frequency bands: 1960 MHz, 2140 MHz, and 2630 MHz. For this application, the recommended matching capacitances values used were from the 2630 MHz operation.
The placement of these matching capacitances is critical. The recommended spacing for ADL5606 matching is provided in the product data sheet for three frequency bands: 1960 MHz, 2140 MHz, and 2630 MHz. For this application, the recommended spacing used was for the 2630 MHz operation. This was further optimized from simulations in Advanced Design System (ADS) for the desired 2400 MHz operation.
Bandpass Filter
The input signal is filtrated by this bandpass filter and centers at 2450 MHz with a 100 MHz bandwidth of operation. It has a frequency of operation from 2400 MHz to 2500 MHz, return loss of 1.5 dB maximum, and return loss of 9.5 dB maximum. The input power to the bandpass filter is at 2 W maximum.
USB Power Management
The LTM8045 is an integrated switching DC to DC converter that contains a current-mode controller, a power switching element, a power coupled inductor, a power Schottky diode, and a modest amount of input and output capacitance.
The device is configured as a SEPIC converter capable of accepting input voltage up to 18 V dc. The output is adjustable between 2.5 V and 15 V. It can provide approximately 430 mA at VIN = 5 V when VOUT = 5 V or −5 V.
Click here to learn more about the CN0417 Evaluation Kit.
Click here to learn more about the ADL5606 amplifier.
Click here to learn more about the LTM8045 DC-DC converter.
