LVDS: Understanding Low Voltage Differential Signaling

LVDS: Understanding Low Voltage Differential Signaling

Nov 29th 2022

LVDS is a method for transmitting display data that makes use of differential signaling at low voltages. Versatile screens, high-definition visuals, fewer connections and higher frame rates are all advantages of these interfaces.

There are three ways in which signals can be transmitted, single-ended mode, common mode, and differential mode. In single-ended mode, the driver and receiver are connected by a line over which data is sent. In contrast, the data is transferred using a single-ended or pair of differential lines in the conventional method. Interferences in the circuits may occur when noise is linked to either the near-end or far-end signal source. A pair with opposing polarities that connects the driver and the receiver to form the differential mode is known as a differential pair or LVDS. Since LVDS uses such differential signaling, information is transmitted as the difference in voltages on a pair of wires, which are then compared at the receiver.

When it comes to data transmission rates, LVDS is clearly distinguished and is faster than options such as RS-422 and RS-485. It is, in fact, so fast that it commonly runs at rates of 655 Mbps but can also run as fast as 1 - 3 Gbits/s. High speeds are crucial in some use cases, particularly for mission critical end products such as medical devices, diagnostic tools, and consumer electronics, and LVDS is a great low cost option to deliver data. In fact, the standard is widely regarded for low power consumption as well, which allows battery powered devices to run longer.

LVDS is applauded for its low power consumption in data transmission - this makes it the perfect interface when you are working on projects in which energy is a primary concern. In fact, it is well known that displays are a primary draw on power, especially when users prioritize backlighting and high resolution displays. With a power draw that is as low as 1.2 V, it is obvious why this is such a popular interface choice. Reduced supply voltages often result in lower power usage since they reduce the voltage across termination resistors and increase current flow.

Compared to single-ended systems, the differential data transmission mechanism employed in LVDS is more resistant to common-mode noise. The benefit of the differential technique is that the receiver, which only considers the difference between the two signals, effectively rejects noise that is coupled onto the two wires as common-mode (the noise appears on both lines equally). Effectively, the noise is removed from or eliminated.

Low system costs and reliability are commonly associated with the LVDS standard. LVDS is cheaper both initially and while operating due to reduced power consumption needs. The design is relatively simple, and its versatility is in high demand, which has allowed associated hardware to drop in price purely due to economies of scale.

In summary, LVDS works by transmitting information using differences in voltage on a pair of wires which allows for relative simplicity, cutting hardware costs and boosting information transmission rates while cutting down on noise.