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19 May 2015

In digital electronics, fan-out is defined as the number of gate inputs that the output of a single logic gate can feed. It is very important in digital systems for a single logic gate to drive other gates or devices. In this case, a buffer can be used between the logic gate and the devices it will drive. Clock buffer is also called as fan-out buffer. The IDT clock buffer clock divider and clock multiplexer portfolio includes devices with up to 27 outputs. Differential outputs such as LVPECL, LVDS, HCSL, CML, HSTL, as well as selectable outputs, are supported for output frequencies up to 3.2 GHz and single-ended LVCMOS outputs for frequencies up to 350MHz.

Modern digital systems often require many high quality clocks at logic levels that are different from the logic level of the clock source. Extra buffering may be required to guarantee accurate distribution to other circuit components without loss of integrity. Many systems require low jitter multiple system clocks for mixed signal processing and timing. The circuit shown in interfaces the ADF4351 integrated phase-locked loop (PLL) and voltage-controlled oscillator (VCO) to the ADCLK948, which provides up to eight low voltage differential signaling (LVDS) outputs from one differential output of the IDT 8SLVD1208-33. The IDT8SLVD1208-33I is characterized to operate from a 3.3V power supply. Guaranteed output-to-output and part-to-part skew characteristics make the IDT8SLVD1208-33I ideal for those clock distribution applications demanding well-defined performance and repeatability. Two selectable differential inputs and eight low skew outputs are available. The integrated bias voltage reference enables easy interfacing of single-ended signals to the device inputs. The device is optimized for low power consumption and low additive phase noise.

Fan-out buffers and clock dividers are general-purpose clock building block devices that can be used in any number of applications. They are ideal for clock and signal distribution in a large variety of systems, from personal computers to consumer electronics or industrial systems, as well as high-performance networking and communications systems.

Increasing Outputs from a Clock Source – [Link]

14 May 2015


Nowadays, laterally diffused metal oxide semiconductor (LDMOS) transistors are widely used for RF Power Amplification and in many applications. A simplified circuit of an LDMOS amplifier bias circuit is shown in the schematic diagram above. The DC Bias on these amplifiers is set by applying a DC voltage to the gate (VGS) and by monitoring the Drain current (IDD). Ideally, this IDD will be constant over temperature, but since the VGS of LDMOS amplifier devices varies with temperature, some type of temperature compensation is required.

The ISL21400 features a precision voltage reference combined with a temperature sensor whose output voltage varies linearly with temperature. The precision 1.20V reference has a very low temperature coefficient, and its output voltage is scaled by an internal DAC (VREF) to produce a temperature stable output voltage that is programmable from 0V to 1.20V. The output voltage from the temperature sensor (VTS) is summed with VREF to produce a temperature dependent output voltage. The maximum voltage supply of the ISL21400 is 5.5V, and the LP2950 voltage regulator drops the LDMOS voltage to 5.5V for the ISL21400 supply. An LC filter is then added to the output of the voltage regulator to ensure no RF energy present on the supply line. The ISL21400 can be tied to a microcontroller or to any I/O connector for PC control and programming.

The RFPA bias control using the ISL21400 is very straightforward. The RFPA uses the Freescale AFT21S140W02GSR3. LDMOS are useful devices for many applications including commercial FM broadcasting and TV power transmitters, cellular and paging communication systems, and military RF and microwave hand-held transceivers.

LDMOS Transistor Bias Control in RF Power Amplifiers – [Link]

21 Apr 2015


by elektor.com:

Following on from the release of their PSoC 4 BLE chip at the Electronica Exhibition last year, Cypress Semiconductor Corp are extending their play in the Bluetooth market with the introduction of their new EZ-BLE module. The module contains the PSoC 4 BLE chip together with two crystals, an on-board chip antenna, RF shielding and passive components, all in a compact 10 mm x 10 mm x 1.8 mm form factor so that designers using the module can apply to add the Bluetooth logo on their products by referring to Cypress’s Qualification Design Identification (QDID) 67366, a unique serial number assigned by the Bluetooth SIG. The module is compliant with wireless regulatory standards in the U.S., Canada, Japan, Korea and Europe and offers a significant saving for designers in development, testing and certification costs.

Cypress Bluetooth Module – [Link]

26 Mar 2015


Martin writes:

The rumors for RFM12B’s end-of-life two years ago seem to have been highly exaggerated now and the popular RF module is still available in abundance. HopeRF has introduced a pin-compatible upgrade, the RFM69CW. The module itself offers improved sensitivity and range compared to the RFM12B (+30%) at the cost of increased power consumption, making it probably a good choice for the receiving end (RFM2Pi), and probably less suited for low power battery operated nodes. The new module supports RSSI for those interested in measuring it.

The new module is more power hungry, and simply replacing a RFM12B on the RFM2Pi v2 or a Funky v3 with it didn’t work; The boards browned out so I had to swap C4 and C7 on the RFM2Pi with 10uF caps and populate the 0805 10uF on Funky v3’s boost regulator circuitry to get it to work. I’ll ship the boards with these refinements from now on so that they are compatible with both the RFM12B and RFM69CW.


Using RFM69CW instead of RFM12B – [Link]

17 Mar 2015

In this video Craig demonstrates his custom DIY RFID smart lock project:

The goal of this project was to design an inexpensive rfid door lock which could be opened via smart phone, and have all activity logged w/o utilizing any 3rd party servers or cloud hosting.

Custom DIY RFID smart lock – [Link]

14 Mar 2015


Microchip Technology Inc., has announced the first in a series of modules for the LoRa technology low-data-rate wireless networking standard. The system is designed to allow Internet of Things (IoT) and Machine-to-Machine (M2M) wireless communication offering a range of more than 10 miles (suburban), a battery life of greater than 10 years, and the ability to connect millions of wireless sensor nodes to LoRa technology gateways. The 433/868 MHz RN2483 is a European R&TTE Directive Assessed Radio Module measuring 17.8 x 26.3 x 3 mm and with 14 GPIOs to provide connections and control for a large number of sensors and actuators.

The RN2483 is also supplied with the LoRaWAN™ protocol stack, allowing connection with the LoRa Alliance infrastructure—including both privately managed local area networks (LANs) and telecom-operated public networks—to create Low Power Wide Area Networks (LPWANs) with nationwide coverage. This stack integration also enables the module to be used with any microcontroller with a UART interface. The RN2483 also uses Microchip’s simple ASCII command interface for easy configuration and control.

Microchip LoRa Network Module – [Link]

11 Mar 2015


by Colin Jeffrey @ gizmag.com:

For the first time in history, a prototype radio has been created that is claimed to be completely digital, generating high-frequency radio waves purely through the use of integrated circuits and a set of patented algorithms without using conventional analog radio circuits in any way whatsoever. This breakthrough technology promises to vastly improve the wireless communications capabilities of everything from 5G mobile technology to the multitude devices aimed at supporting the Internet of Things (IoT).

World’s first fully digital radio transmitter built purely from microprocessor technology – [Link]

10 Mar 2015


Bring back the nostalgia with a tube transmitter! Are you interested in building this AM shortwave transmitter? Most parts used are still available, download circuit diagram for details. You can find more RF projects here: www.stationqrp.com

AM shortwave transmitter – [Link]

2 Mar 2015


One of the simplest digital modulation schemes in current use is the Frequency-shift keying (FSK). FSK is similar to Frequency Modulation or FM except that the modulating signal is a binary pulse stream that varies between two discrete voltage levels rather than a continuously changing analog waveform. In FSK, two discrete frequencies are used to represent the binary digits 0 and 1.

The heart of the circuit consists of two Wien-bridge oscillators built using a dual op amp LM1458, for the two frequencies. The two frequencies are enabled corresponding to digital data using two switches in HEF4016BP. The control lines of these switches are logically inverted with respect to each other using one of the switches in HEF4016BP as an inverter, so as to enable only one oscillator output at a time. The digital bit stream is used to control the analog switches as shown. Since the switching frequency limit of HEF4016BP is 40 MHz, high-data rates can be easily accommodated. This method comes in handy when expensive FSK generator chips are not readily available; also, the components used in this circuit are easily available off the shelf and are quite cheap.

FSK was originally used to transmit teleprinter messages by radio (RTTY) but can be used for most other types of radio and landline digital telegraph. Currently, FSK is commonly used in Caller ID and remote metering applications.

Low-cost FSK Generator – [Link]

24 Feb 2015


By David Szondy @ gizmag.com:

A global economy brings many benefits, but it also makes international terrorism extremely difficult to combat. With more goods passing through the world’s shipping terminals and airports than ever before, hunting explosives with large, static detectors or teams of inspectors armed with detecting devices and reagents is a bottleneck that increases the chances of evasion. To help US counterterrorism efforts, GE has developed RFID stickers that act as wireless, battery-free explosives detectors that can be placed almost anywhere.

GE RFID tech turns stickers into explosives detectors – [Link]





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